NEW YORK — A subsidiary of Pfizer has extended the expiration date of its tender offer to acquire all outstanding shares of common stock of King Pharmaceuticals.

Parker Tennessee's tender offer now is scheduled to expire Jan. 21, as certain conditions to the tender offer wouldn't have been satisfied by the previously scheduled expiration date — which was Dec. 17 — including the expiration or earlier termination of any waiting period under the Hart-Scott-Rodino Antitrust Improvements Act.

Other terms and conditions of the offer remain unchanged. Pfizer and King expected the deal to be completed by first quarter 2011.

Back in October, Pfizer announced it would acquire Bristol, Tenn.-based King for $3.6 billion, or $14.25 per share.